My first line of research when I have to use something new is: Can I get a fixed bill every month? What happens if I use more than that, can I limit surprises?

My first line of research when I have to use something new is: Can I get a fixed bill every month? What happens if I use more than that, can I limit surprises? If not, I will find something else. We are also very careful with building us into "free" google services after the map surprise a few years ago. That cost us a lot of money in the end.